Substrate of LCD device and method of manufacture thereof

ABSTRACT

An image display area is defined in a main surface of a first substrate, and a terminal area is defined outside the display area. A plurality of first bus lines are arranged on the display area of the main surface of the first substrate. A first insulating layer covers the first bus lines on the main surface of the first substrate. The first bus lines correspond to external terminals on the terminal area of the first substrate, respectively. The external terminals are connected electrically with the corresponding first bus lines, respectively, through first contact holes that pass through the first insulating layer to the upper surface of the first bus lines. The external terminals are covered with a protective insulating layer in such a manner that their ends near the border of the first substrate remain uncovered.

TECHNICAL FIELD

[0001] The present invention relates to a substrate of an LCD (LiquidCrystal Display) device and a method of manufacture thereof, and moreparticularly to a substrate of an LCD device having connection terminalsto an external circuit disposed near the border of the substrate and toa manufacture method thereof.

BACKGROUND ART

[0002]FIG. 6 shows a cross sectional view of a conventional activematrix type liquid crystal display device, showing a connection terminalto an external circuit. A gate insulating film 101 is formed on thesurface of a glass substrate 100. The gate insulating film 101 is usedas the gate insulating film of a thin film transistor (TFT) of eachpixel. A drain bus line 102 is formed on the gate insulating film 101.The drain bus line 102 is connected to a drain terminal of the TFT.

[0003] An insulating film 103 is formed on the gate insulating film 101,covering the drain bus line 102. An external terminal 104 is formed inan area near an outer periphery of the insulating film 103. The externalterminal 104 is connected to the drain bus line 102 via a contact hole105 formed through the insulating film 103.

[0004] An opposing substrate 110 is disposed spaced by a gap from theglass substrate 100. The opposing substrate 110 is fixed at a positionnear its peripheral area to the glass substrate 100 with adhesive 115.The upper surface of the external terminal 104 is exposed in aperipheral area of the substrate outside of the adhesive 115. Liquidcrystal material 118 is filled in the gap between the glass substrate100 and opposing substrate 110.

[0005] When the opposing substrate 110 is fixed to the glass substrate100, the border of the opposing surface 110 is aligned approximatelywith the border of the glass substrate 100, as viewed along a substratenormal direction. After the opposing substrate 110 is fixed to the glasssubstrate 100, a region 110 a near the border of the opposing substrate110 is cut off so that the external terminal 104 can be connected to anexternal drive circuit.

[0006] While the region 110 a near the border of the opposing substrate110 is cut off, the external terminal 104 may be damaged anddisconnected in some cases. A common electrode is formed on the opposingsurface of the opposing substrate 110. Conductive dusts may be generatedwhile the region 110 a is cut off and may short-circuit the externalterminal 104 and common electrode.

DISCLOSURE OF THE INVENTION

[0007] It is an object of the present invention to provide a substrateof a liquid crystal display device and a manufacture method thereof,capable of making external terminals hard to be damaged while a regionnear the border of a substrate opposing another substrate with theexternal terminals is cut off.

[0008] According to one aspect of the present invention, there isprovided a substrate of a liquid crystal display device, comprising: afirst substrate having an image display area defined on a principalsurface of the first substrate and a terminal area defined in a partialarea outside of the image display area; a plurality of first bus linesdisposed in the image display area on the principal surface of the firstsubstrate; a first insulating film disposed over the principal surfaceof the first substrate, the first insulating film covering the first buslines; an external terminal formed in the terminal area of the firstsubstrate for each of the first bus lines, the external terminal beingelectrically connected to a corresponding one of the first bus lines viaa corresponding one of first contact holes formed through the firstinsulating film and reaching an upper surfaces of the first bus lines;and a protective film made of insulating material covering a partialupper surface of the external terminal so as not to cover at least anupper surface of the external terminal near an outer peripheral area ofthe first substrate.

[0009] Since a portion of the external terminal is covered with theprotective film, it is possible to suppress damages of the externalterminal during the processing and working of the later processes. Sincea portion of the external terminal in an outer peripheral area is notcovered with the protective film, connection between the externalterminal and circuit can be established in this portion.

[0010] According to another aspect of the present invention, there isprovided a method of manufacturing a liquid crystal display devicecomprising the steps of: preparing a first substrate having an imagedisplay area defined on a principal surface of the first substrate and aterminal area defined in a partial area outside of the image displayarea, the first substrate being formed with: a plurality of first buslines disposed in the image display area on the principal surface of thefirst substrate; a first insulating film disposed over the principalsurface of the first substrate, the first insulating film covering thefirst bus lines; an external terminal formed in the terminal area of thefirst substrate for each of the first bus lines, the external terminalbeing electrically connected to a corresponding one of the first buslines via a corresponding one of first contact holes formed through thefirst insulating film and reaching an upper surfaces of the first buslines; a protective film made of insulating material covering a partialupper surface of the external terminal so as not to cover at least anupper surface of the external terminal near an outer peripheral area ofthe first substrate; a plurality of second bus lines formed in the imagedisplay area and crossing the first bus lines; a pixel electrode formedin the image display area and disposed at each cross point between thefirst and second bus lines; and a switching element for connecting eachof the pixel electrodes to a corresponding one of one of the first andsecond bus lines, a conduction state of the switching element beingcontrolled by a signal applied to a corresponding one of the other ofthe first and second bus lines; preparing a second substrate formed witha common electrode on a surface thereof; disposing the first and secondsubstrates so that the surface of the second substrate with the commonelectrode is spaced apart by some distance from the principal surface ofthe first substrate, and fixing the first and second substrates with asealing member in such a manner that the sealing member does not coverat least a partial upper surface of the protective film near an outerperipheral area of the first substrate; and cutting a portion of thesecond substrate near a border of the second substrate so that a newborder of the cut second substrate passes an inner area of theprotective film as viewed along a direction normal to the firstsubstrate.

[0011] Since a portion of the external terminal is covered with theprotective film, the external terminal is hard to be damaged while theperipheral portion of the second substrate is cut. It is thereforepossible to suppress the generation of conductive defects of theexternal terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a plan view of a liquid crystal display device accordingto a first embodiment of the invention.

[0013]FIGS. 2A and 2B are cross sectional views of a liquid crystaldisplay illustrating the effects of projection patterns.

[0014]FIG. 3 is a cross sectional view of the liquid crystal displaydevice of the first embodiment.

[0015]FIGS. 4A to 4F are cross sectional views of a substrateillustrating a method of manufacturing a TFT substrate of the liquidcrystal display device of the first embodiment.

[0016]FIGS. 5A and 5B are cross sectional views of a substrateillustrating a method of manufacturing a TFT substrate of a liquidcrystal display device according to a second embodiment.

[0017]FIG. 6 is a cross sectional view of a conventional active matrixtype liquid crystal display device showing a connection terminal to anexternal circuit.

BEST MODE FOR PRACTICING THE INVENTION

[0018]FIG. 1 is a plan view of a homeotropic type liquid crystal displaydevice of the first embodiment. An image display area 2 is defined onthe surface of a glass substrate 1, and a terminal area 3 is definedoutside of the image display area 2. A plurality of gate bus lines 5extend in the row direction (lateral direction) as viewed in FIG. 1.Between adjacent two gate bus lines 5, a capacitance bun line 6 isdisposed extending in the row direction. A gate insulating film coversthe gate bus lines 5 and capacitance bun lines 6. On this gateinsulating film, a plurality of data bus lines 7 are disposed extendingin the column direction (vertical direction) as viewed in FIG. 1.

[0019] A thin film transistor (TFT) 10 is formed at each cross pointbetween the gate bus line 5 and data bus line 7. The drain electrode ofTFT 10 is connected to a corresponding data bus line 7. The gate busline 5 also servers as the gate electrode of a corresponding TFT 10.

[0020] An interlayer insulating film covers the data bus lines 7 andTFTs 10. A pixel electrode 12 is disposed in an area surrounded by twogate bus lines 5 and two data bus lines 7. The pixel electrode 12 isconnected to the source region of a corresponding TFT 10.

[0021] An auxiliary capacitor sub-line 14 branched from the capacitancebun line 6 extends along the border of the pixel electrode 12. Thecapacitance bun line 6 and auxiliary capacitor sub-line 14 form anauxiliary capacitor together with the pixel electrode 12. The potentialof the capacitance bun line 6 is fixed.

[0022] As the potential of the data bus line 7 changes, the potential ofthe pixel electrode 12 changes because of capacitive coupling byparasitic capacitance. In the structure shown in FIG. 1, since the pixelelectrode 12 is connected via the auxiliary capacitor to the capacitancebus line 6, a potential change of the pixel electrode 12 can be reduced.

[0023] On the opposing surfaces of the glass substrate 1 with TFTs andthe opposing substrate, first projection patterns 16 and secondprojection patterns 18 are formed along zigzag patterns extending in thecolumn direction. In order to distinguish the first projection patterns16 from the second projection patterns 18, the first projection pattern16 is shown hatched in FIG. 1. The first projection patterns 16 aredisposed at an equal interval along the row direction, and their bentpoints are positioned on the gate bus lines 5 and capacitance bun lines6. Each second projection pattern 18 has approximately a similar patternto that of the first projection pattern 16 and is disposed generally atthe middle between adjacent two first projection patterns 16.

[0024] Data terminals 20 are disposed in a terminal area 3 lower in FIG.1 in correspondence with data bus lines 7, and in a terminal area 3 leftin FIG. 1, gate terminals 21 are disposed in correspondence with gatebus lines 5. Each data terminal 20 is connected to a corresponding databus line 7 via a contact hole 24. Each gate terminal 21 is connected toa corresponding gate bus line 5 via a contact hole 25. The gate bus line5 and data bus line 7 are connected to external drive circuits via thegate terminal 21 and data terminal 20, respectively.

[0025] A protective film 26 is disposed traversing generally a centralarea of the data terminal 20 along the row direction. The protectivefilm 26 does not cover the upper surface of the data terminal 20 in anouter peripheral area near the border of the glass substrate 1.

[0026] With reference to FIGS. 2A and 2B, the function of the first andsecond projection patterns 16 and 18 will be described.

[0027]FIG. 2A is a cross sectional view of a liquid crystal displaydevice when a voltage is not applied. On the opposing surface of theglass substrate 1, first projection patterns 16 are formed, and on theopposing surface of the opposing substrate 36, second projectionpatterns 18 are formed. A vertical alignment film 28 is formed on theopposing surfaces of the glass substrate 1 with TFTs and the opposingsubstrate 36, covering the projection patterns 16 and 18. Between theglass substrate 1 with TFTs and the opposing substrate 36, liquidcrystal material 29 containing liquid crystal molecules 30 is filled in.Liquid crystal molecules 30 have negative dielectric anisotropy. On theouter sides of the glass substrate 1 and opposing substrate 36,polarizer plates 31 and 32 are disposed in a cross Nicol layout.

[0028] While voltage is not applied, liquid crystal molecules 30 arealigned at a right angle relative to the substrate surface. Liquidcrystal molecules 30 a on the slopes of the first and second projectionpatterns 16 and 18 tend to be aligned at a right angle relative to theslopes. Therefore, the liquid crystal molecules 30 a on the slopes ofthe first and second projection patterns 16 and 18 are aligned obliquelyrelative to the substrate surface. However, since the liquid crystalmolecules 30 are aligned vertically in a broad area of the pixel, a goodblack display state can be obtained.

[0029]FIG. 2B is a cross sectional view of the liquid crystal displaywhen voltage is applied to make liquid crystal molecules 30 oblique,i.e., when the liquid crystal display device takes a half-tone displaystate. As shown in FIG. 2A, the liquid crystal molecules 30 a inclinedalready are inclined further in the same inclination direction. Liquidcrystal molecules 30 near the inclined molecules 30 a are inclined inthe same inclination direction under the influence of inclination of theinclined molecules 30 a. Accordingly, the liquid crystal molecules 30between the first and second projection patterns 16 and 18 are disposedin such a manner that their longitudinal axis (director) is directedalong a straight line extending from the lower left to upper right asviewed in FIG. 2B. The liquid crystal molecules 30 left to the firstprojection pattern 16 and right to the second projection pattern 18 aredisposed in such a manner that their longitudinal axis is directed alonga straight line extending from the lower right to upper left as viewedin FIG. 2B.

[0030] A plurality of domains having liquid crystal molecules with thesame inclination direction is therefore defined in one pixel. The firstand second projection patterns 16 and 18 define the boundaries of thedomains. By disposing the first and second projection patterns 16 and 18in parallel in the substrate plane, two types of domains can be formed.In the example shown in FIG. 1, since the first and second projectionpatterns 16 and 18 are bent, domains of four types in total can beformed. Since a plurality of domains is formed in one pixel, view anglecharacteristics in the half-tone display state can be improved.

[0031]FIG. 3 is a cross sectional view of the liquid crystal displaydevice shown in FIG. 1. Diagram portions right and left to the centralbroken area shown in FIG. 3 correspond to cross sectional views takenalong on-dot chain lines A-A and B-B shown in FIG. 1, respectively. ATFT substrate 35 and an opposing substrate 36 are disposed in parallelspaced apart by a gap.

[0032] First, the structure of the TFT substrate 35 will be described.Gate bus lines 5 are formed on the opposing surface of a glass substrate1. The gate bus line 5 has a two-layer structure of an Al film having athickness of 10 nm and a Ti film having a thickness of 50 nm. A gateinsulating film 40 is formed over the glass substrate 1, covering thegate bus lines 5. The gate insulating film 40 is a SiN film having athickness of 400 nm.

[0033] An active region 41 is formed on the gate insulating film 40,overriding the gate bus line 5. The active region 41 is a non-dopedamorphous Si film having a thickness of 30 nm. A channel protective film42 is formed on the surface of the active region 41 in an area above thegate bus line 5. The channel protective film 42 is a SiN film having athickness of 140 nm. The channel protective film 42 is patterned so asto cover the channel region of TFT 10 as viewed in FIG. 1.

[0034] A source electrode 44 and a drain electrode 46 are formed on theupper surface of the active region 41 at the region on both sides of thechannel protective film 42. Each of the source and drain electrodes 44and 46 has a lamination structure of an n⁺-type amorphous Si film havinga thickness of 30 nm, a Ti film having a thickness of 20 nm, an Al filmhaving a thickness of 75 nm and a Ti film having a thickness of 80 nmstacked in this order. TFT 10 is constituted of the gate bus line 5,gate insulating film 40, active region 41, source electrode 44 and drainelectrode 46.

[0035] In the terminal area 3, one end portion of a data bus line 7 isdisposed on the gate insulating film 40. The data bus line 7 has thesame lamination structure as that of the drain electrode 46 formed inthe image display area 2. The amorphous Si film formed at the same timewhen the active region 41 was formed is left under the data bus line 7.An insulating film 48 is formed on the gate insulating film 40, coveringTFT 10 and data bus line 7. The insulating film 48 is a film made ofSiN, having a thickness of 330 nm.

[0036] A pixel electrode 12 is formed on the insulating film 48. Thepixel electrode 12 is a film made of indium tin oxide (ITO), having athickness of 70 nm, and is connected to the source electrode 44 via acontact hole 50 formed through the insulating film 48.

[0037] A first projection pattern 16 is formed on the pixel electrode 12and insulating film 48. The first projection pattern 16 is made of photoresist. An alignment film 28 covers the uppermost layer in the imagedisplay area 2.

[0038] In the terminal area 3, a data terminal 20 is formed on theinsulating film 48. The data terminal 20 is patterned when the pixelelectrode 12 is patterned. The data terminal 20 is connected to the databus line 7 via a contact hole 24 formed through the insulating film 48.A protective film 26 covers a partial upper surface of the data terminal20. A partial region, near the border of the glass substrate 1, of theupper surface of the data terminal 20 is exposed.

[0039] Next, the structure of the opposing substrate 36 will bedescribed. A light shielding film 52 made of Cr or the like is formed ina predetermined area of the opposing surface of a glass substrate 27. Acommon electrode 54 made of ITO is formed on the opposing surface of theglass substrate 27, covering the light shielding film 52. An alignmentfilm 28 covers the surface of the common electrode 54 in the imagedisplay area 2. In the terminal area 3, the common electrode 54 isexposed.

[0040] The opposing substrate 36 is fixed at its peripheral position tothe TFT substrate 35 with adhesive 56. The adhesive 56 hermeticallyseals the gap between the TFT substrate 35 and opposing substrate 36.Liquid crystal material 29 is filled in the gap between the TFTsubstrate 35 and opposing substrate 36. The liquid crystal material 29has negative dielectric anisotropy. The adhesive 56 is fixed to the TFTsubstrate 35 in an inner area than the area where the protective film 26is located . The adhesive 56 may be made in contact with the protectivefilm 26.

[0041] Next, a method of adhering the TFT substrate 35 and opposingsubstrate 36 will be described. When the opposing substrate 36 is fixedto the TFT substrate 35, the border of the opposing substrate 36 isaligned approximately with the corresponding border of the TFT substrate35, as viewed along a substrate normal direction. After the opposingsubstrate 36 is fixed to the TFT substrate 35, a peripheral region 36 aof the opposing substrate 36 is cut off.

[0042] The border of the opposing substrate 36 after the peripheralregion 36 a is cut off passes the inside of the protective film 26.Therefore, it is possible to suppress the generation of damages or thelike of the data terminal 20 on the TFT substrate 35 side while theopposing substrate 36 is scribed. It is therefore possible to suppressthe generation of inferior conduction of the data terminal 20 andimprove the manufacture yield. It is also possible to prevent shortcircuits between data terminals 20 to be caused by dusts generated byscribing the common electrode 54.

[0043] Next, with reference to FIGS. 4A to 4F, a method of manufacturingthe TFT substrate 35 shown in FIG. 3 will be described.

[0044] Processes up to the state shown in FIG. 4A will be described. Onthe surface of the glass substrate 1, an Al film having a thickness of100 nm and a Ti film having a thickness of 50 nm are sequentiallyformed. These films may be formed through sputtering. The two layers ofthe Al film and Ti film are patterned by photolithography techniques toleave a gate bus line 5. The Al film and Ti film are etched throughreactive ion etching (RIE) using mixture gas of BCL₃ and CL₂.

[0045] Processes up to the state shown in FIG. 4B will be described. Agate insulting film 40 of SiN having a thickness of 400 nm is formed onthe glass substrate 1, covering the gate bus line 5. A non-dopedamorphous Si film 41 a having a thickness of 30 nm is formed on the gateinsulating film 40. For example, the gate insulating film 40 andamorphous Si film 41 a are formed by plasma enhanced chemical vapordeposition (PE-CVD).

[0046] A SiN film having a thickness of 140 nm is formed on theamorphous Si film 41 a by PE-CVD. This SiN film is patterned throughphotolithography techniques to leave a channel protective film 42. Usingthe gate bus line 5 as a photo mask, light is radiated from the bottomof the glass substrate 1 so that the edge of a resist pattern parallelto the row direction in FIG. 1 can be defined. The edge parallel to thecolumn direction in FIG. 1 is defined through exposure using a usualphoto mask. The SiN film may be etched by wet etching using bufferedhydrofluoric acid or by RIE using fluorine gas.

[0047] Processes up to the state shown in FIG. 4C will be described. Ann⁺-type amorphous Si film having a thickness of 30 nm is formed over thewhole substrate surface by PE-CVD, covering the channel protective film42. On this n⁺-type amorphous Si film, a Ti film having a thickness of20 nm, an Al film having a thickness of 75 nm and a Ti film having athickness of 80 nm are sequentially formed through sputtering. Thelayers from the uppermost Ti layer to the non-doped amorphous Si film 41a are etched and patterned by RIE using mixture gas of BCL₃ and CL₂. Inthis case, in an area above the gate bus line 5, the channel protectivefilm 42 functions as an etching stopper layer.

[0048] An active region 41 of non-doped amorphous Si is therefore lefton the gate insulating film 40, overriding the gate bus line 5. A sourceelectrode 44 and a drain electrode 46 are also left on the upper surfaceof the active region 41 at the region on both sides of the protectivefilm 42. In the terminal area, a data bus line 7 is left.

[0049] Processes up to the state shown in FIG. 4D will be described. Aninsulating film 48 made of SiN having a thickness of 330 nm is formedover the whole substrate surface by PE-CVD. A contact hole 50 is formedthrough the insulating film 48 to expose a partial upper surface of thesource electrode 44. At the same time, a contact hole 24 is formed toexpose a partial upper surface of the data bus line 7 near the borderthereof.

[0050] Processes up to the state shown in FIG. 4E will be described. AnITO film having a thickness of 70 nm is formed over the whole substratesurface. For example, the ITO film is formed by DC magnetron sputtering.This ITO film is patterned to leave a pixel electrode 12 and a dataterminal 20. The ITO film is etched using the etchant including oxalicacid.

[0051] Processes up to the state shown in FIG. 4F will be described. Aresist film is formed over the whole substrate surface and patterned toleave first projection patterns 16 in the image display area, and aprotective film 26 in the terminal area. Next, an alignment film 28 isformed in the image display area.

[0052] During the processes shown in FIG. 4F of the first embodimentmethod, the protective film 26 is formed at the same time when the firstprojection pattern 16 is formed. It is therefore possible to form theprotective film 26 without increasing the number of processes.

[0053] By using the protective film 26, identification symbols such as aproduct type, a product number and a lot number may be formed. Forexample, in an area other than the image display area, characters, barcodes, mosaic two-dimensional bar codes or the like may be formed.

[0054] Next, a method of manufacturing a liquid crystal display deviceaccording to the second embodiment will be described by paying attentionto different points from the first embodiment manufacture method.

[0055] In the process shown in FIG. 4A, the gate bus line 5 is made ofAINd alloy which contains 2 mol % of Nd. As compared to the laminationstructure of Al and Ti of the first embodiment, a wiring resistance canbe reduced.

[0056] In the process shown in FIG. 4C, the source electrode 44, drainelectrode 46 and data bus line 7 have the three-layer structure of ann⁺-type amorphous silicon film having a thickness of 30 nm, a Ti filmhaving a thickness of 20 nm and an Al film having a thickness of 300 nm.As compared to the four-layer structure of the first embodimentincluding the n⁺-type amorphous silicon film, Ti film, Al film and Tifilm, the Al film can be made thicker so that the wiring resistance ofthe data bus line 7 can be reduced. If a thick Al film is etched by RIE,burnt deposits of resist or the like may be generated. In such a case,it is preferable that the Al film is wet-etched.

[0057] In the second embodiment, since the uppermost layer of the sourceelectrode 44 is the Al film, good electrical contact with the ITO filmcannot be obtained. To prevent bad electrical contact between the sourceelectrode 44 and the ITO film, the following processes are differentfrom the first embodiment.

[0058] As shown in FIG. 5A, an insulating film 48 made of SiN having athickness of 330 nm is formed over the whole substrate surface. In thiscase, in order to form a tapered contact hole in a later process, it ispreferable that the insulating film 48 is formed under the conditionsthat an etching rate in the upper layer is faster than that in the lowerlayer.

[0059] An ITO film is formed on the insulating film 48 and patterned toleave a pixel electrode 12 and an external connection portion 20 a forthe data terminal.

[0060] As shown in FIG. 5B, contact holes 50 and 24 are formed throughthe insulating film 48, the contact hole 50 exposing a partial uppersurface of the source electrode 44 and the contact hole 24 exposing apartial upper surface of the data bus line 7. A Ti film having athickness of 20 nm is formed over the whole substrate surface, and onthis Ti film, a photo resist film is formed and patterned to leaveresist patterns 60, 61 and 62.

[0061] The resist pattern 60 has a pattern similar to the firstprojection pattern 16 shown in FIG. 1. In FIG. 1, one first projectionpattern 16 traverses a plurality of pixel electrodes. However, in thesecond embodiment, in order not to make adjacent pixel electrodes beconnected via the resist pattern 60, this resist pattern 60 is cut atthe region between the adjacent two pixel electrodes 12.

[0062] The resist pattern 61 continuously covers from the area above thecontact hole 50 to the end portion of the pixel electrode 12. The resistpattern 62 continuously covers from the area above the contact hole 24to the partial area above the external connection portion 20 a.

[0063] By using these resist patterns 60, 61 and 62 as a mask, the Tifilm is etched. The resist pattern 60 and a Ti film 65 left under theresist pattern 60 constitute a first projection pattern 16. A Ti film 66left under the resist pattern 61 makes the pixel electrode 12electrically connect the source electrode 44. A Ti film 67 left underthe resist pattern 62 makes the external connection portion 20 aelectrically connect the data bus line 7. An internal connection portion20 b made of the Ti film 67 and the external connection portion 20 aconstitute a data terminal 20. An alignment film 28 is formed coveringthe image display area.

[0064] The first projection pattern 16 of the second embodiment has theconductive Ti film 65 as the lower layer. However, in this case, sincethe first projection pattern 16 is cut at the region between adjacentpixel electrodes 12, there is no short circuit between adjacent pixelelectrodes 12.

[0065] In the second embodiment, the pixel electrode 12 made of ITO isnot in direct contact with the uppermost Al film of the source electrode44, but is connected to the Al film via the Ti film 66. Good electricalconnection between the pixel electrode 12 and source electrode 44 cantherefore be obtained.

[0066] The resist pattern 62 covering the inner connection portion 20 bof the data terminal 20 provides a similar function to that of theprotective film 26 of the first embodiment shown in FIG. 3. While theperipheral portion of the opposing substrate is cut off, the dataterminal 20 can be protected and the generation of inferior conductionof the data terminal 20 can be suppressed. Similar to the firstembodiment, by using the resist pattern 62, identification symbols suchas a product type, a product number and a lot number may be formed.

[0067] The present invention has been described in connection with thepreferred embodiments. The invention is not limited only to the aboveembodiments. It is apparent that various modifications, improvements,combinations, and the like can be made by those skilled in the art.

What we claim are:
 1. A substrate of a liquid crystal display device,comprising: a first substrate having an image display area defined on aprincipal surface of said first substrate and a terminal area defined ona partial area outside of the image display area; a plurality of firstbus lines disposed on the image display area on the principal surface ofsaid first substrate; a first insulating film disposed over theprincipal surface of said first substrate, said first insulating filmcovering said first bus lines; an external terminal formed on theterminal area of said first substrate for each of said first bus lines,said external terminal being electrically connected to a correspondingone of said first bus lines via a corresponding one of first contactholes formed through said first insulating film and reaching an uppersurfaces of the first bus lines; and a protective film made ofinsulating material covering a partial area of an upper surface of saidexternal terminal so as not to cover at least a partial area of theupper surface of said external terminal near a border of said firstsubstrate.
 2. A substrate of a liquid crystal display device accordingto claim 1 , further comprising: a plurality of second bus lines formedon the image display area and crossing said first bus lines; a pluralityof pixel electrodes formed on the image display area and disposedcorresponding to cross points between said first and second bus lines;and a plurality of switching elements corresponding to said pixelelectrodes, each of switching elements connecting corresponding pixelelectrode to one of corresponding first and second bus lines, aconduction state of said switching element being controlled by a signalapplied to the other of corresponding first and second bus lines.
 3. Asubstrate of a liquid crystal display device according to claim 2 ,wherein: said switching elements are covered with said first insulatingfilm, said pixel electrodes are disposed on said first insulating film,and each pixel electrode is connected to corresponding switching elementvia a second contact hole formed through said first insulating film; andsaid external terminals and said pixel electrodes are made of samematerial.
 4. A substrate of a liquid crystal display device according toclaim 2 , further comprising a ridge-like projection patterns disposedover said pixel electrodes and made of same material as said protectivefilm.
 5. A substrate of a liquid crystal display device according toclaim 3 , further comprising a ridge-like projection patterns disposedover said pixel electrodes and made of a same material as saidprotective film.
 6. A substrate of a liquid crystal display deviceaccording to claim 2 , wherein: said switching elements are covered withsaid first insulating film; the substrate further comprises: pixelconnection lines, each electrically connecting each of said pixelelectrodes to corresponding switching element via a second contact holeformed through said first insulating film; and a cover film for coveringan upper surface of said pixel connection lines; each of said externalterminals includes an external connection portion disposed on theterminal area and an internal connection portion for electricallyconnecting the external connection portion to corresponding first busline; and said protective film covers an upper surface of the internalconnection portions.
 7. A substrate of a liquid crystal display deviceaccording to claim 6 , wherein said pixel connection lines and saidinternal connection portions are made of same material, said pixelelectrodes and the external connection portions are made of samematerial, and said protective film and said cover film are made of samematerial.
 8. A substrate of a liquid crystal display device according toclaim 6 , further comprising ridge-like projection patterns disposedover said pixel electrodes, said bank-like projection pattern having alamination structure of a lower layer made of same material as saidpixel connection lines and an upper layer made of same material as saidcover film.
 9. A substrate of a liquid crystal display device accordingto claim 7 , further comprising a ridge-like projection patternsdisposed over said pixel electrodes, said ridge-like projection patternshaving a lamination structure of a lower layer made of same material assaid pixel connection lines and an upper layer made of same material assaid cover film.
 10. A liquid crystal display device comprising: a firstsubstrate having an image display area defined on a principal surface ofsaid first substrate and a terminal area defined in a partial areaoutside of the image display area; a plurality of first bus linesdisposed on the image display area on the principal surface of saidfirst substrate; a first insulating film disposed over the principalsurface of said first substrate, said first insulating film coveringsaid first bus lines; external terminals formed on the terminal area ofsaid first substrate, each of the external terminals being correspondingto each of said first bus lines, being electrically connected tocorresponding first bus line via a first contact hole formed throughsaid first insulating film and reaching an upper surface of the firstbus line; a protective film made of insulating material covering apartial area of upper surfaces of said external terminals so as not tocover at least partial areas of the upper surfaces of said externalterminals near a border of said first substrate a second substratefacing the principal surface of said first substrate and spaced apart bya gap from the principal surface, said second substrate having a commonelectrode formed on a surface facing said first substrate and beingdisposed so that a partial border of said second substrate passes aninner area of said protective film as viewed along a direction normal tosaid second substrate; a sealing member for fixing said second substrateto said first substrate in a peripheral area of said second substrateand hermetically sealing the gap between said first and secondsubstrates; and liquid crystal material filled in the gap between saidfirst and second substrates.
 11. A method of manufacturing a liquidcrystal display device comprising the steps of: preparing a firstsubstrate having an image display area defined on a principal surface ofsaid first substrate and a terminal area defined in a partial areaoutside of the image display area, the first substrate being formedwith: a plurality of first bus lines disposed on the image display areaon the principal surface of the first substrate; a first insulating filmdisposed over the principal surface of the first substrate, the firstinsulating film covering said first bus lines; an external terminalformed on the terminal area of the first substrate for each of the firstbus lines, the external terminal being electrically connected tocorresponding first bus line via a first contact hole formed through thefirst insulating film and reaching an upper surface of the first busline; a protective film made of insulating material covering a partialarea of an upper surface of the external terminal so as not to cover atleast a partial area of the upper surface of the external terminal neara border of the first substrate; a plurality of second bus lines formedon the image display area and crossing the first bus lines; a pixelelectrode formed on the image display area and disposed at each crosspoint between the first and second bus lines; and a switching elementfor connecting each of the pixel electrodes to one of correspondingfirst and second bus lines, a conduction state of the switching elementbeing controlled by a signal applied to the other of corresponding firstand second bus lines; preparing a second substrate formed with a commonelectrode on a surface thereof; disposing the first and secondsubstrates so that the surface of the second substrate with the commonelectrode is spaced apart by a gap from the principal surface of thefirst substrate, and fixing the first and second substrates with asealing member in such a manner that the sealing member does not coverat least a partial area of an upper surface of the protective film nearthe border of the first substrate; and cutting off a portion of thesecond substrate near a border of the second substrate so that a newborder of the cut second substrate passes an inner area of theprotective film as viewed along a direction normal to said firstsubstrate.